Computer aided design (CAD) is used in many different fields. For example, an object of manufacture may be represented in a CAD or similar computer program to assist with the design, manufacture and analysis of that object. In such programs, three-dimensional objects may be represented by millions or tens of millions of triangles, where each triangle can be represented by three vertices, each of which having three coordinate values. Complex objects may be represented by multiple objects or members in a mated arrangement. Each of the members of the object may be represented by a plurality of triangles, and the object can be defined by the combination of its members.
It may be desirable to determine a surface area of an outer layer of an object, for example, to estimate the amount of paint needed to coat the object. For a simple, one-member object, the surface area of the object may be determined based on the plurality of triangles (e.g., summing the area of the triangles). For multi-member objects, however, the sum of the area of the triangles of each of its members may result in an inaccurate estimate as such a determination fails to account for the area of the mated portions, which will not be on the outer layer of the object. Thus, there is a need for a more accurate method of determining the surface area of the outer layer of multi-member objects.